In analog signal processing applications, such as in automotive, wireless communication, or networking applications, it is often necessary to amplify incoming analog signals before they can be processed. Amplifying incoming analog signals is necessary for optimum processing, and typically involves passing input signals through an amplifier.
Programmable gain amplifiers (PGAs) are circuits that allow an input signal to be boosted to a programmed optimum gain level. PGAs can be either single-stage, for lower speed applications requiring only a coarse gain control, or multi-stage, for higher speed applications requiring a fine control of the gain. However, PGAs that operate at higher speeds consume a greater amount of power. Thus, there are competing design constraints between operating speed and power consumption in a PGA. In addition, many circuits may require amplifying more than one analog input signal. This is typically accomplished using multiple dedicated PGAs, one for each analog input signal. However, the demand for smaller and more inexpensive circuit packages stifles the ability to provide high speed programmable amplification to multiple analog signals. Using a dedicated PGA for each channel also requires each of the PGAs to precisely match each other in performance characteristics. The result is an undesired increase in circuit components, and thus die-area, as well as power consumption.